Dr Paul Tixier, a research fellow at Deakin’s Centre for Integrative Ecologywithin the School of Life and Environmental Sciences, is part of the research team that made the discovery while monitoring the dive behaviour of a killer whale (Orcinus orca) in subantarctic waters in South Georgia.

Researchers used satellite-linked location and dive-profile tags on the killer whale, which was taking Patagonian toothfish from commercial longlines – a fishing technique using a long line with baited hooks to capture target fish.

Patagonian toothfish are a deep-water fish and are considered a delicacy, with the majority of the fish caught legally by Australian boats sold overseas to Japanese, Chinese and US markets.

Dr Tixier said the results were striking, with the killer whale diving to 1087 metres – the greatest depth ever recorded for that species and around 300 metres deeper than previously recorded.

“The diving ability of the species has been underestimated, but we found the whales were diving significantly deeper and faster when taking from fishing lines compared to when foraging naturally,” he said . . .

At least half of the world’s killer whale populations are doomed to extinction due to toxic and persistent pollution of the oceans, according to a major new study.

Although the poisonous chemicals, PCBs, have been banned for decades, they are still leaking into the seas. They become concentrated up the food chain; as a result, killer whales, the top predators, are the most contaminated animals on the planet. Worse, their fat-rich milk passes on very high doses to their newborn calves.

PCB concentrations found in killer whales can be 100 times safe levels and severely damage reproductive organs, cause cancer and damage the immune system. The new research analysed the prospects for killer whale populations over the next century and found those offshore from industrialised nations could vanish as soon as 30-50 years.

Among those most at risk are the UK’s last pod, where a recent death revealed one of the highest PCB levels ever recorded. Others off Gibraltar, Japan and Brazil and in the north-east Pacific are also in great danger. Killer whales are one of the most widespread mammals on earth but have already been lost in the North Sea, around Spain and many other places.

“It is like a killer whale apocalypse,” said Paul Jepson at the Zoological Society of London, part of the international research team behind the new study. “Even in a pristine condition they are very slow to reproduce.” Healthy killer whales take 20 years to reach peak sexual maturity and 18 months to gestate a calf.

PCBs were used around the world since the 1930s in electrical components, plastics and paints but their toxicity has been known for 50 years. They were banned by nations in the 1970s and 1980s but 80% of the 1m tonnes produced have yet to be destroyed and are still leaking into the seas from landfills and other sources.

The international Stockholm Convention on Persistent Organic Pollutants came into force in 2004 to tackle the issue, but Jepson said the clean-up is way behind schedule. “I think the Stockholm Convention is failing,” he said. “The only area where I am optimistic is the US. They alone produced 50% of all PCBs, but they have been getting PCB levels down consistently for decades. All we have done in Europe is ban them and then hope they go away.”

The researchers said PCBs are just one pollutant found in killer whales, with “a long list of additional known and as yet unmeasured contaminants present”. Further problems for killer whales include the loss of key prey species such as tuna and sharks to overfishing and also growing underwater noise pollution.

The new research, published in the journal Science, examined PCB contamination in 351 killer whales, the largest analysis yet. The scientists then took existing data on how PCBs affect calf survival and immune systems in whales and used this to model how populations will fare in the future. “Populations of Japan, Brazil, Northeast Pacific, Strait of Gibraltar, and the United Kingdom are all tending toward complete collapse,” they concluded.

Lucy Babey, deputy director at conservation group Orca, said: “Our abysmal failures to control chemical pollution ending up in our oceans has caused a killer whale catastrophe on an epic scale. It is essential that requirements to dispose safely of PCBs under the Stockholm Convention are made legally binding at the next meeting in May 2019 to help stop this scandal.” Scientists have previously found “extraordinary” levels of toxic pollution even in the 10km-deep Mariana trench in the Pacific Ocean.

“This new study is a global red alert on the state of our oceans,” said Jennifer Lonsdale, chair of the Wildlife and Countryside Link’s whales group. “If the UK government wants its [proposed] Environment Act to be world-leading, it must set ambitious targets on PCB disposal and protect against further chemical pollution of our waters.”

The research shows that killer whale populations in the high north, off Norway, Iceland, Canada and the Faroes, are far less contaminated due to their distance from major PCB sources. ”The only thing that gives me hope about killer whales in the longer term is, yes, we are going to lose populations all over the industrialised areas, but there are populations that are doing reasonably well in the Arctic,” said Jepson.

If a global clean-up, which would take decades, can be achieved, these populations could eventually repopulate empty regions, he said, noting that killer whales are very intelligent, have strong family bonds and hunt in packs. “It is an incredibly adaptive species – they have been able to [live] from the Arctic to the Antarctic and everywhere in between.”

He praised the billion-dollar “superfund” clean-ups in the US, such as in the Hudson River and Puget Sound, where the polluter has paid most of the costs: “The US is going way beyond the Stockholm Convention because they know how toxic PCBs are.”

Tight maritime security in Sabah’s east coast and strict regulation on international trade of marine mammals will make it difficult for outsiders to hunt killer whales in the state waters.

Marine mammals expert Dr Lindsay Porter, when contacted, told the New Straits Times that it was impossible for hunters to escape with a large marine mammal without being noticed.

Porter, who works with the World Wide Fund for Nature, deals with dolphins, whales, porpoises, and dugongs. She also works on issues of marine mammal harvesting and hunting for food, bait or traditional uses.

On Jan 21, the NST reported on the sightings of a pod of orcas – the largest species of dolphin – near Sipadan Island. The killer whales were spotted by a group of divers.

Following the report, readers expressed concern that publicising such report would attract sea poachers or marine mammal hunters into the area.

“Perhaps this is a risk but I am somewhat baffled as to who would have a vessel large enough and explosive harpoons available to kill a killer whale?

“They are not small. Small rifle fire unlikely to do much damage and quite frankly, what market would there be for dead killer whales? And live ones, it would be extremely difficult to catch one on the east coast of Sabah,” responded Porter.

“There is a strict regulation on international trade of marine mammals, even if someone could catch and hold a killer whale…there are also regular patrols by security forces as well as Fisheries and Wildlife agencies.

“Sabah’s east coast is heavily patrolled by maritime security (possibly) making it very difficult for outsiders to try and come into our waters for such purposes,” she said, stressing killer whales are large and fast predators.

With respect to concerns that some people may exploit killer whales in Sabah waters, Porter said it was unlikely that anyone from the state could or would opportunistically hunt or kill orcas.

While pointing there was some evidence that traditional hunts for small dolphins occurred in the past, she said this was different as it was easier than hunting a killer whale.

“I do this work for the International Whaling Commission that is interested in all aspects of humans using marine mammals for food or any other purpose.

“We have done extensive work on where and who in Asia would or has exploited marine mammals (including hunting them or killing them if they get tangle in fishing nets).

“Sabah has a very low reporting rate of any consumption or bait use. Only some of the coastal people may use dolphin teeth as currency or dowry but this is poorly documented.

“This was why I find it unlikely that Sabahans would hunt the killer whales as they neither have the skills nor equipment to do so and there is no traditional demand or market.”

She however noted that In Indonesia, the people of Lamellera are famous for their daring attempts to harpoon sperm whales by using traditional spears.

For experienced hunters like these people, Porter said they might be capable of successfully harpooning a killer whale.

On presence of orcas in Sabah waters, she noted there had been several sightings of in Sabah waters but none of encounters were in the news.

“It is great to see marine mammals and the oceans being featured in news.

“I don’t think that reporting the sighting of these amazing oceanic predators increases the risk of anyone trying to harm or hunt these animals.

“I think instead that reporting this species, highlighting Sabah’s rich and diverse marine wildlife and reminding everyone that the oceans are ours to look after is a great privilege that the many means of news media broadcasting can provide.”

The sighting of a pod of orcas by a group of divers in Sipadan waters last Sunday was not a first, as the marine mammals have been spotted in Sabah waters several times before.

This was shared by other divers following New Straits Times’ online report on the recent encounter near the world-renowned island.

Downbelow Marine and Wildlife Adventures managing director Richard Swann told the NST that there had been several sightings in the past, wherein orcas were seen passing through waters off Sipadan and Layang-Layang islands.

“Although I have yet to encounter them, I know others who have. They spotted a pod of orcas in Sipadan waters a few years back.

“The killer whales were seen chasing dolphins, but I am not sure if (the divers) were able to document the event, because the boat… could not catch up (with the mammals),” Swann said.

He added that another group of divers spotted killer whales near Layang-Layang in March last year.

Swann, who is a PADI (Professional Association of Diving Instructors) Platinum course director, has been diving in Sabah for over 10 years.

During his dives in the state, he has encountered whale sharks and dolphins.

“I (saw) melon-headed whales (often referred to as ‘blackfish’ or ‘false killer whales’) in 2005 in Sipadan waters, but I missed the killer whales.

“At that time, there could have been hundreds of dolphins… probably more than a thousand (different) species. As for melon-headed whales, it is hard to say (how many of them there were), as they seemed to be very cautious and kept their distance.

“Every now and again, there is a huge number of dolphins passing through and predators naturally follow, on occasion.

“It can be breath-taking, (it’s) like some kind of marine convention, and they socialise when they come together, unless being hunted – then they are just on full speed,” said Swann.

Last Sunday, 32-year-old diver Faridzul Adzli Mad Adim encountered about eight orcas and took videos of them swimming and jumping out of the water.

His videos, which he posted on his Facebook page, have garnered more than 8,000 views.

Meanwhile, Sabah Fisheries Director Ahemad Sade said presence of killer whale in Sabah waters was not common but noted they have been spotted in waters off Semporna.

“As for now we can tentatively identify it as killer whale by looking at the white spot under the dorsal fin (based on Faridzul’s video).

“The orcas could have used our waters as part of their migratory route since waters off Sipadan is quiet deep.

“The area is also a migratory route for yellow fin and big eye tuna,” he said.

While it carries the name ‘whale’, this marine mammal belongs to the dolphin family and is its largest member.

Although killer whales tend to inhabit cold oceans, they can be found in all of the world’s major seas, from the Arctic and Antarctica, to various tropical regions located in and around the equator.

They usually prey on squid, octopus, seal, sea lion, sea otter, ray, dolphin, shark, baleen whale and of course, bony fishes. Occasionally, turtles and seabirds, including penguins, are added to their diet.